1. Field of the Invention
The present invention relates to a directional microphone operating according to the electrostatic or electrodynamic transducer principle. In such a directional microphone, the pickup effect is determined by at least one phase-shifting delay line section between the rear side of the active transducer diaphragm and at least one sound entry opening provided in the housing at a distance behind the plane of the diaphragm. The directional microphone includes at least one accoustic element coupled to the delay line section.
2. Description of the Prior Art
Directional microphones are known and described, for example, in German Pat. No. 821 217. These directional microphones have several undesirable disadvantages. Since the phase-shifting delay line sections are generally designed in such a way that they are effective over the entire range of audibility, the frequency response and the sensitivity are impaired because of the compromises which must be made. The close talking effect which occurs in these direction microphones constructed as pressure-gradient sound pickups is particularly troublesome. The close talking effect resides in that an extreme sensitivity increase occurs in the bass range which substantially falsifies the sound impression. In addition, the pressure-gradient pickups are particularly sensitive to explosive sounds which lead to the so-called pop noise.
In other prior art directional microphones of the same type, additionally acoustic elements are included which are coupled to the delay line section. In these cases, the pickup pattern is influenced and changed. In the prior art references directed to these directional microphones, the problem of the close talking effect is not addressed. Due to the construction of these microphones, this problem does not arise.
It is, therefore, the primary object of the present invention to provide a directional microphone which avoids the disadvantages of the known microphone with pickup pattern.